US1763325A - Vulcanization of rubber - Google Patents

Description

' Patented June 16,1930

UNITED STATES.

DONALD E. POWERS, OF PEN NS GROVE,

PATENT OFFICE NEW JERSEY, ASSIGNOR TO E. I. PONT DE WARE N Drawing.

\ This invention relates to an improvement inthe vulcanization of rubber and more partieu'larly to the use of a new compound as an accelerator of vulcanization to be more specifically referred to hereinafter.

I have discovered that benzo thiazole monosulfides constitute excellent accelerators for the vulcanization of rubber and provide a superior rubber product. I have also found 10 a convenient and suitable process for the formation of this type of accelerator compound. The application of these accelerators or agents in the vulcanization of rubber may be carried out in 'a manner already generally known in the art. That is to say, the formulas, mode of mixing, etc., may be varied very widely in making use of this new class of accelerators. t

I, therefore, give merely by way of a suit- 'able embodiment of the invention the following composition of stock:

' .Parts Amber crepe 50 Smoked sheets 50 Zinc oxide u 3 Sulphur a 3.5 Thiazyl monosulfide 1 The usual manipulative procedure adopted in the vulcanization of rubber may, of course,

be applied in this case also and the temperatures offvulcanization used will, of course, be

controlled in a suitable manner with the un;

' derstanding that a lower temperature of vulcanization may be used if a longer time of 5 curing and a larger percentage of the accelerator is employed, and that when using higher temperatures a shorter time of cure or less accelerator may be used.

I have found that various benzo thiazole 40 monosulfides may be thus employed and for purposes of illustration I include the follow- 'ing table to show the general effects of certam accelerators, although it is to be understood that these values are not limited, and

may, of course, vary to some extent, according V'ULCANIZA'IION OI RUBBER Application filed August 31, 1926. Serial No- 132,895.

to the manner of curing, the quantities of ace celerators and general conditions of compound ng and vulcanization.

Cure g t s r a Elongabreak g Pressure (lbs/sq minutes (pounds) Benzo thiazyl monosulphide- 20 40 2 420 800 3-methu1 benzo thiazyl mono- 20 40 3 1040 815 sulphlde 30 30 3, 230 810 Naphtho thiazyl monosulphide. 20 40 3,060 815 I have also discovered a method of preparing the accelerators to be used in the carrying out of this invention, and as an example I present a process for the production of benzo thiazole monosulfide as follows:

Two thousand pounds of sodium mercapto benzo thiazole prepared by dissolving mercapto benzo thiazole in the calculated amount of dilute caustic soda solution, is made up to a weight of twenty thousand pounds of aqueous solution. This solution is preferably cooled below'10 C. and while being agitated, six hundred and fifty pounds of cyanogen chloride are added using the usual precautions for handling this material and avoid.

ing over-heating. The benzo thiazole monosulphide separates as a yellow crystalline waterdnsoluble product. It may be readily recrystallized from alcohol, but the product as it separates from the aqueous solution is of very good purity. The monosulphide is then filtered and dried.-

may also be starting with the substituted benzo thiazole. Of particular importance is the methyl benzo thiazole monosulfide prepared from 3-methyl benzothiazole. Alkyl, hydroXy,v or alkoxy substituted benzo thiazole monosulfides may also be pre ared and used to aid the vulcanization of ru ber or to act as accelerators therein, as the case may be, and these and other Substituted benzo thiazole monosulfides prepared in a similar manner thiazole mono-sulphide.

modifications in this class of compounds are to be understood as being com rise'd i-withm the scope of my inventlon. e 7probable mechanism of the reaction for the formation of these compounds is "as-follows:

- a \-s-m+on.nmae

As many apparently widely diflerentem bodiments of this invention may be made without departing from the spirit thereof, it

is to be understood that I do not limit myself to the foregoing examples or description, ex-

cept as indicated in the following patent claims.

'I claim: 1 1; The process of treating rubber, which comprises vulcanizing said rubber in the presence of di benzo thiazole mono-sulphide;

2. The process of treating rubber, which comprises heating the same with a vulcanizing agent in'the presence of a small proportion of a reaction product of a mercapto benzo thiazole and a cyanogen halide.

3. The process of vulcanizing rubber comprising heating the same in the presence'of I a vulcanizingagent and a yellow crystalline product" formed by the reaction of cyanogen chloride and the sodium salt of=mercaptobenzo-thiazole, said product being soluble in alcohol. .and insoluble in water.

4. The. process of treating rubber which comprises vulcanizing said rubber in the presence of a member of the group consisting of 'di benzo thiazole mono-sulphide, di-3-methyl benzo thiazole mono-sulphide and dinaphtho In testimony whereof I aflix my signature.

DONALD H. POWERS.